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1. Install bash completion extension package# dnf -y install bash-completion# reboot2. Disabling SELinuxFirst, disable selinux.　selinux is a feature that improves auditing and security in Linux, but when enabled, it can limit the behavior of services and the contents of the configuration considerably.Therefore, it is basically a case of invalidation in many cases.SELinux operating modesEnforcing : SELinux functionality is enabled and access control is enabledPermissive : SElinux will warn, but no access restrictions will be placeddisabled : Both SElinux function and access control are

1. Setting up a remote connection via SSHSSH is a service for connecting remotely to a server and is basically running immediately after the OS is installed, but the default settings are somewhat insecure.Here we will configure the default settings to increase the security of SSH connections.1.1 SSH service configuration file changesThe SSH service configuration file is "/etc/ssh/sshd_config".2. Firewall (Firewalld) settingsIn Oracle, the firewall is firewalld configured by default and enabled during OS installation.To briefly explain "firewalld," when setting communication control policies, communication permission/blocking rules are applied to predefined zones, and these zones are then assigned to each NIC (network adapter).3. Remote connection from WindowsConfiguration in WindowsStart the setup for remote connection from Windows, using "Tera Term" as the terminal emulator.Start Tera Term, cancel the startup screen, and then select "New Connection" from "File" in the Tera Term menu.

SSH connection with authentication using public key Creation of public and private key pairsCreate a public/private key pair for a user connecting to the Linux server using OpenSSH.Use ssh-keygen to create key pairs.Creation of public/private key pairs is performed with remote login user privileges.If you do not specify the destination and file name, id_ed25519 and id_ed25519.pub will be created in /home/(user name)/.ssh/. On the way, enter the password for the key.

1. FTP Server1.1 Vsftpd Install# dnf -y install vsftpd1.2 Vsftpd configurationSave vsftpd.conf with .bak# cp /etc/vsftpd/vsftpd.conf /home/huong/vsftpd.conf.bak2. vsftpd SSL/TLSConfigure Vsftpd to use SSL/TLS2.1 Create self-signed certificatesThis work is not required if you are using a trusted, legitimate certificate such as Let's Encrypt.3. File server installation with SambaBuild a file server with access rights that requires user authentication with Samba.Installation Procedure①Create shared folders with access rights that require user authentication②Accessible group creation③Creation of users belonging to accessible groups④Configuration File Edit

1.Apache2 Install1.1 httpd Install# dnf -y install httpd1.3 Virtual Host SettingsAssign and configure the domain name [FQDN] to the document root [/var/www/html/[FQDN]] directory for virtual host operation2. Confirmation of CGI Script Usage①Confirmation of CGI availability3. PHP installation and configuration①Install# dnf -y install php php-mbstring php-pear4. Digest authentication with Apache2Since Basic Authentication, a well-known authentication authorization method for http, sends authentication information in plain text, there is a risk of ID and password leakage if the packet is intercepted.On the other hand, Digest Authentication encrypts and transmits authentication information, so there is almost no risk of information leakage.

clamav(anti-virus)1.Clam AntiVirus Install# dnf -y install clamav clamd clamav-update2.Edit Clam AntiVirus configuration fileMail Server Installation1. Postfix1.1 InstallInstall Postfix and build an SMTP server# dnf -y install postfixMail Server : Postfix + Clamav + clamav-milter+SpamAssassin1.Real-time scanning of e-mails①clamav-milter InstallVirus checks are performed on the mail server side using Clam AntiVirus.The mail server and Clam AntiVirus are linked using clamav-milter.

1. SSL Certificate Acquisition ( Let's Encrypt )Install the latest open ssl# dnf install openssl-devel1.1 advance preparation1.Package management system Snappy installationSince the SSL certificate issuing tool "certbot" of Let's Encrypt is recommended to be installed using "snap" after 2021, install Snapd first.(Can also be installed the traditional way with dnf or yum)2. Converting Apache to httpsInstall the following# dnf -y install mod_ssl2.1 Edit ssl.conf file3. SSL/TLS (Let's Encrypt) settings on the mail server3.1 Obtaining a certificate for the mail serverObtain a certificate for the mail server, but it cannot be obtained in the same way as above, so the following with the "--standalone" option fails.

Mysql8 Install＃ dnf -y install mysql-serverCreate a new charset.cnf with the following contentsWordPress Install1. Create database for Word PressAs an example, assume database [wp_db] database user [wp_user] password [?W123456]

SuricataSURICATA IDS/IPS is an open source IDS that monitors communications on the network and detects suspicious traffic.The basic mechanism is signature-based, so it can detect predefined unauthorized communications. Suricata is also characterized by its ability to provide protection as well as detection.SNORT3 Snort is an open source network intrusion detection system that can perform real-time traffic analysis and packet logging on IP networks.It can perform "protocol analysis," "content search," and "matching" and can be used to detect a variety of attacks such as buffer overflows, stealth port scans, CGI attacks, SMB probes, OS fingerprinting attempts, semantic URL attacks, and server message block probes. detection.

Tripwire1.Download and installation# cd /usr/local/src# wget https://rpmfind.net/linux/epel/9/Everything/x86_64/Packages/t/tripwire-2.4.3.7-13.el9.x86_64.rpm# rpm -Uvh tripwire-2.4.3.7-13.el9.x86_64.rpmChkrootkit①Download and install chkrootkit# cd /usr/local/src# wget https://launchpad.net/chkrootkit/main/0.55/+download/chkrootkit-0.55.tar.gz# tar xvf chkrootkit-0.55.tar.gzLogwatch①Install# dnf install logwatchIntroduce disk usage check script1. Script Creation# cd /var/www/system# vi disk_capacity_check.sh

1.Website data backup1-1.Backup under /var/www/html①Create backup script file2.MySQL database backup①Create backup script file# cd /var/www/system# vi db_my_backup.sh3.Restore backup files under html① Store HTML backup files in "/ (root)" directory# cd /var/www/backup/html_bak# cp html_back_20220610.tar.gz / ←Specify the backup file with the latest date4.Restore Mysql backup file①Save the database backup file to any directory and（In the example, the directory is "/var/www/backup/db_bak".）Extracting data# cd /var/www/backup/db_bak

Tripwire1.Download and installation# cd /usr/local/src# wget https://rpmfind.net/linux/epel/9/Everything/x86_64/Packages/t/tripwire-2.4.3.7-13.el9.x86_64.rpm# rpm -Uvh tripwire-2.4.3.7-13.el9.x86_64.rpmChkrootkit①Download and install chkrootkit# cd /usr/local/src# wget https://launchpad.net/chkrootkit/main/0.55/+download/chkrootkit-0.55.tar.gz# tar xvf chkrootkit-0.55.tar.gzLogwatch①Install# dnf install logwatchIntroduce disk usage check script1. Script Creation# cd /var/www/system# vi disk_capacity_check.sh

Mysql8 Install＃ dnf -y install mysql-serverCreate a new charset.cnf with the following contentsWordPress Install1. Create database for Word PressAs an example, assume database [wp_db] database user [wp_user] password [?W123456]